Buffer Objects

Python objects implemented in C can export a “buffer interface.” These functions can be used by an object to expose its data in a raw, byte-oriented format. Clients of the object can use the buffer interface to access the object data directly, without needing to copy it first.

Two examples of objects that support the buffer interface are bytes and arrays. The bytes object exposes the character contents in the buffer interface’s byte-oriented form. An array can also expose its contents, but it should be noted that array elements may be multi-byte values.

An example user of the buffer interface is the file object’s write() method. Any object that can export a series of bytes through the buffer interface can be written to a file. There are a number of format codes to :cfunc:`PyArg_ParseTuple` that operate against an object’s buffer interface, returning data from the target object.

More information on the buffer interface is provided in the section Buffer Object Structures, under the description for :ctype:`PyBufferProcs`.

Buffer objects are useful as a way to expose the data from another object’s buffer interface to the Python programmer. They can also be used as a zero-copy slicing mechanism. Using their ability to reference a block of memory, it is possible to expose any data to the Python programmer quite easily. The memory could be a large, constant array in a C extension, it could be a raw block of memory for manipulation before passing to an operating system library, or it could be used to pass around structured data in its native, in-memory format.

Buffer related functions

MemoryView objects

A memoryview object is an extended buffer object that could replace the buffer object (but doesn’t have to as that could be kept as a simple 1-d memoryview object). It, unlike :ctype:`Py_buffer`, is a Python object (exposed as memoryview in builtins), so it can be used with Python code.